CVE-2026-3254

Improper Restriction of Rendered UI Layers or Frames in GitLab

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.11 before 18.11.1 that under certain conditions could have allowed an authenticated user to load unauthorized content into another user's browser due to improper input validation in the Mermaid sandbox.

Affected

GitLab

CVSS v3.1 GITLAB

3.5 LOWCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

EPSS

0.26% chance of exploitation in the next 30 days, 16th percentile

Published

2026-04-22

Proof-of-concept exploits (1)

• https://hackerone.com/reports/3572752

References

• CVE Record
• NVD entry